Process for the manufacture of rails with hardened heads



Oct. 20, 1931. H. KURZ. 2

PROCESS EOR THE MANUFACTURE OF RAILS WITH HARDENED HEADS Filed July '7, 1928 Jul /anion Hem/10f; Kurz "I W" A far/fey Patented Oct. 20, 1 931 P ATE NT OFFICE HEINRICH KURZ, OF iDUISBURG-RUHBORT, GERMANY PROCESS FOR THE MANUFACTURE OF RAILS WITH HARDENED HEADS Application filed July 7, 1928, Serial No. 291,036, and in Germany August 22, 1927.

When manufacturing rails with hardened heads and rolled articles of a similar kind,

where certain areas or zones areto be im-- hardness and tensile strength occur simul taneously with diminished elongation. Be-

, tween the extreme values of these martensite structures, and the pearlite structures occurr i ng' with slow cooling, with decreased hardness and tensile strength accompanied by in- I creased elongation, there occur characteristic intermediate sta es viz. troostite, osmondits and sorbite whose elongation'increases in the same sequence, whereas the hardness and the tensile strength fall.

The kinds of structures can be obtained:

1 (1) Either in such a manner that the rapidly chilled steel is by means of repeated heating subjected to an additional tempering up to the degree of improvement'it is desired to obtain.

(2) In such a manner that b suitably regulating the time of cooling, t e desired degree of hardening is obtained straight away.

The practical carrying out of these kinds of improvement is accompanied however, in the case of a rolled article of considerable length, as will be seen from the following, by great technical difliculties. It isof course economically more favorable if the heat still inherent in the rolled material after the roll-' ing process, can be utilized for hardening purposes. If the improvement is effected according to the first of the. two mentioned methods, then the material will have to be subjected to re-heating to quite definite degrees of temperature after the chilling. It is however very difficult to achieve a simple and effective attainment of these most favorable temperatures exactly.

Similarly with the second method difliculties are met with in regulating the cooling speed, as accurate and continuous control of temperature arerequired with this method, WhlCh is hardly practicable. But the greatest difliculty occurs in such cases where it is not desirable for manufacturing and technical reasons to harden the whole cross-sectional area. 7 The brittleness in steel chilled in such manner is very great, so that in the case of rails for instance, a hardening of the whole cross-sectional area of the rail head must be, for reasons of safety, avoided. 4

The invention relates in thefirst instance to a new process, preferably for treating rails, where the running surface only is subjected to wear and tear, in such a manner that a greater degree of hardness and consequently a greater resistance'to wear and tear 1s imparted to those parts. It becomes thus possible to obtain in the work piecethe railthe tenacity or toughness of the nontreated steel simultaneously with the hardness of the treated steel. Such a process possesses the advantage that the rails can be rolled from material comparatively poor in carbon, which after being treated according to the present process, is superior to the usual carbon containing materials, both as regards tensile strength and resistance to wear and tear. Thus the safety of railway. working is appreciably improved.

In the case of the improved process, the finished rail on leaving the mill, moves as has already been similarly proposed, and preferably after its end has een sawn ofi', slowly ast nozzles, the liquid spray issuing from w ich effects a rapid chilling, at the places to be hardened, for instance at the running surface of the head of the rail. The quantity of liquid used depends on the sectional area of the rolled material on the depth of the desired hardening zoneandon the tem erature at which the rail leaves the rolls. t only requires a short sequence of experiments to determine this quantity, for the case in point. The depth of thehardening can be regulated bythe s eed at which the rail passes the sprayand yadjustment of theliquid supply. Bythis rapid chilling at the places to be hardened a martensite structure is produced there, the heat remaining in the non-treated part of the cross-section flowing off to the chilled part, where it may produce a tempering efi'ect. Rails so hardened show as a rule a gradual transition from the hardness structure at the running surface to the normal non-treated ferritepearlite structure in the centre portion of the head.

The invention provides that in such a process the rolled material is subjected to the cooling or the chilling treatment while lying down on the side, and that the part to be especially subjected to the treatment is exposed to a substantially horizontal spray of. the cooling medium. Thus it becomes possible to prevent the rail head to be treated from getting out of reach of the jets or sprays of the cooling medium, even when a bend or twist occurs in the rail, which may be in various ways unsymmetrical in its cross section.

By reason of the laid down position of the rail, the latter remains always in a horizontal position owing to its own weight, so that the horizontal spray of cooling medium impinges on the head everywhere and the head is consequently uniformly hardened.

In accordance with the invention also, the possibility of a bending or warping of the rail isfurther reduced by the fact that the rail foot, in addition to the head is subjected to chilling treatment so as to obtain an initial straightening. This cooling is effected at the same time that the head of the rail is chilled for hardening purposes. About two or three additional jets or sprays are, for this purpose, provided opposite the chilling sprays for the head. This embodiment of the process is to be recommended when the head of the rail contains essentially more material than the foot. The cooling jets directed against the sole of the foot abstract'a certain amount of heat from it, with the consequence that the rail during the cooling can hardly, and certainly not to an inadmissible extent, bend or warp, and can in consequence be handled later on in an easier manner.

A. further object of the invention, is to provide a modification of the process described, for the purpose of manufacturing hardened head-channel rails. The novelty consists therein, that the treatment of the running surface of the rail is carried out by means of the cooling medium separately from the treatment of the check flange by the coolingmedium. In this manner it is possible to fulfill the different conditions prevailing for the hardening treatment both of the running surface and of the check flange, an advantage that may be of importance in the case of curved rails.

By maintaining constant high pressure of the cooling medium, the substantially horiteaasaa well as the speed at which the rail passes the sprays and the localization of the sprayed area of the work in relation to the path along which the rolled material has to travel.

An especial uniformity of hardening can be achieved in that any superfluous cooling medium which may possibly collect on the rolled material is removed from it by means of acurrent of some compressed medium, preferably air or steam directed on the top side of the web' of the laid down rail by means of blow pipes grouped in the same manner as the hardening jets or nozzles.

An apparatus, suitable for carrying the new process into effect, and especially adaptable to the most varied cross-sectional shapes and dimensions in the rolled material, as well as to the most varied processes of hardening, is described hereinafter by way of example only.

These possibilities are created especially by reason of the fact that horizontal groups of hardening jets or sprays for the production of a substantially horizontal veil of the cooling medium are arranged alongside the path travelled by the material leaving the rolls. These @groups of hardening jets or sprays are adapted to be brought into or out of their operative position separately. Further cooling nozzles or jets for the cooling medium are so arranged that the rolled material, when travelling past the above mentioned nozzles or jets is subjected to an additional cooling treatment of the sole of the rail foo By combining the various hardening jets or nozzles into groups that can be brought into or out of their operative positions individually, the operation of the process is greatly simdplified, whereas by reason of the fact that sai hardening jets or nozzles can be each separately regulated, opened or shut, the improved-process'has the necessary fiexibilityof regulation. This flexibilit of regulation is further increased when t e orientation of each single hardenin nozzle or jet of a group can be separately sety swivelling said single jet in relation to the piping forming the other jet of said group.

A blast of air or steam under pressure is directed against the top side of the web of the laid down rail through blow pipes, each of which is attached to a hardening spray.

The operation of the process according to i the present invention is further greatly simplified by the fact that, on the one hand, the mechanism for controlling the supply of cooling medium to the hardening nozzles or jets is coupled to the mechanism for controlling the supply of the pressure medium (air l 7 web of the laid down rail, so as to provide a I zles or jets forming a group and all the blow to said grou common control for both supplies, and, on the other hand, that acommon control mechanism is provided for bringing simultaneously intoor out of action all the hardening nozpipes for the pressure medium corresponding In a corresponding manner it is. finally possible to connect the mechanism for controlling the supply of cooling medium used for cooling the rail foot with the above first mentioned common control. Q

The accompanying drawings illustrate the invention and at the same time show an embodiment of apparatus for carrying the process into effect.

Figure 1 is anend view of said embodiment.

, Figure 2 is a view similar to Figure 1, but

in this case the hardening nozzles are shown in an inclined position which enables them to harden directly the check flange of a channel-head rail while the running surface of the head of said rail is hardened only indirectly by convection.

Figure 3 is a front view of a separate hardening nozzle with an attached blow pipe. After leaving the rolls (not shown) the rail is at a temperature of about 1100 C. and various types of known spraying means are placed adjacent the rolls to reduce the temerature of the rail so that the rail is' not too hot for the subsequent hardenin treatment. The rail '10 is then passed in a origitudinal direction as to the length thereof over a hotbed 11 provided with a subjacent trough 12 or other suitable drainage means. guide 13 is Standing with respect to the hot bed 11 and abuts the rail 10 in its longitudinal travel.

The main supply of cooling medium passes throu h a longitudinal pipe 14 to a plurality of in ividually swinging spray groups arranged along the longitudinal path of the rail. Each hardening spray comprises two vertical branch-pipes 15 and 16 (Fig. 3), connected to a rotatable section of main supply pipe 14 corresponding to a group of hardening sprays and a nozzle 17 connected at the lower ends of the vertical branch-pipes 15 and 16. Swivel flanges 18 and 19 are provided near the lower end of both branchpipes 15 and 16', respectively, to allow adjustment of the orientation of each individual spray against the particular part of the rail to. be treated, according to requirements. K

A blast of air or' steam is conducted through blow pipes such as 20 arranged to rotate or swing with each spray and attached to vertical pipe 15 by brackets such as 21. As many pipes 20 as there are nozzles 17 in a group are connected to a rotatable section of a supply pipe 22 corresponding in length with arotatable section of the main supply pipe 14 and each of said pipes 20 is bent into such a form'that the-blast of air-or steam is directed against the upper side of the web of the lying own rail 10, when the nozzle 17 is brought in its operative position.

Aplurality of stationary spray pipes 23,

Each branch-pipe 15, 16 is provided with a valve (not shown) independently of the fact that these branch-pipes are conjointly supplied by means of a common control. The mounting, individual regulating and common control arrangements for the various sprays and pipes maybe such as are quite fully described in application Serial Number 37 0,699, divided from this present application and filed June 13, 1929.

blow pipe 20, to clear the wa when" the rail is being removed sideways a ter the hardening treatment, is shown in dotted lines in Figure 1.

The quantities ofcoolin medium supplied through the sprays 17 an 23, and the quantity of blasting medium supplied through .blowpipe 20, will depend on the characteristics required of the rail and the nature of "the hardening treatment accordingly necessary. Also 17, as efiected b swivelling about the flanges 1-8 and 19 will e determined by the nature of the rail head and the particular part thereofto' be treated; j What I claim and desire to secure by Letters Patent of the United States is:

1. A process for hardening the heads of rails by the action of a cooling medium which comprises passing .the rail in a longitudinal direction and subjecting only the head thereof to the hardening treatment by means of a .dium.

2. A process for hardening the heads of The raised position of the nozzle 17 and the orientation of each spray nozzle rails by the action of a cooling medium which comprises conveying the rail in the direction of the length thereof, hardening only the top of the head of 'said rail by subjecting the .same to a substantiallyhorizontal spra of cooling medium while cooling the sole 0 the foot of said rail with an additional spray of said cooling medium thereby minimizing the tendency in the rail to bend due to the hardening treatment. V A process for hardening channel head rails by the action of a cooling medium which comprises conveying the rail in the direction of its length and hardening the running surface of said rail by subjecting the-same to a substantially horizontal spra of cooling-me dium, the check flange of sai rail being only substantially horizontal spray of cooling me- 0 indirectly cooled and not hardened by the cooling medium.

4. A process for hardening channel head rails by the action of a cooling medium which comprises conveying the rail in the direction of its length, hardening the running surface of said rail by subjecting the same to a substantially horizontal spray of cooling medium, the check flange of said rail being free from direct impinging of said cooling medium and simultaneously cooling the sole of the foot of said rail with an additional spray of said cooling medium, thereby minimizing bending of the rail during the treatment,

5. A process for hardening the heads of rails by the action of a cooling medium which comprises conveying the rail in the direction of the length thereof, hardening only the top of the head of said rail by subjecting the same to a substantially horizontal high pressure spray of cooling medium and cooling the sole of the foot of said rail with an additional spray of said cooling medium, thereby minimizing the tendency in the rail to bend due to the hardening treatment.

6. A process for hardening the' heads of rails by the action-of a cooling medium which comprises conveying continuously the rail laid on its side in the direction of its length, hardening only a part of the head of said rail by subjecting said part to a substantially horizontal spray of cooling medium and varying the quantity and direction of said spray of cooling medium hardenin a part of the rail head to vary the degree of hardening and the position of said hardened part, respectively.

7. A process for hardening the heads of rails by the action of a cooling medium which comprises conveying continuously the rail laid on its side in the direction of its length, hardenin only a part of the head of said rail by subjecting said art to a substantially horizontal spray of 000 ing medium and subjecting laterally the rail to the cleaning action of a high pressure blasting medium.

8. A process for hardening channel head rails by the action of a cooling medium which comprises conveying the rail in the directio" of its length, hardening the running surface of said rail by subjecting the same to a substantially horizontal spray of cooling medium, the check flange of said rail being free from direct impinging of said cooling medium, cooling the sole of the foot of said rail with an additional spray of cooling medium and subjecting the rail to a high pressure blasting medium to clean the surfaces of the rail.

HEINRICH KURZ.

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